/*
 * Returns a new XMLHttpRequest object, or false if this browser
 * doesn't support it
 */
function newXMLHttpRequest()
{
  var xmlreq = false;
  if (window.XMLHttpRequest)
  {
    // Create XMLHttpRequest object in non-Microsoft browsers
    xmlreq = new XMLHttpRequest();
  }
  else if (window.ActiveXObject)
  {
    // Create XMLHttpRequest via MS ActiveX
    try
    {
      // Try to create XMLHttpRequest in later versions
      // of Internet Explorer
      xmlreq = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e1)
    {
      // Failed to create required ActiveXObject
      try
      {
        // Try version supported by older versions
        // of Internet Explorer
        xmlreq = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (e2)
      {
        // Unable to create an XMLHttpRequest with ActiveX
      }
    }
  }
  return xmlreq;
}

/*
 * Returns a function that waits for the specified XMLHttpRequest
 * to complete, then passes its XML response
 * to the given handler function.
 * req - The XMLHttpRequest whose state is changing
 * responseXmlHandler - Function to pass the XML response to
 */
function getReadyStateHandler(req, responseXmlHandler) 
{
  // Return an anonymous function that listens to the
  // XMLHttpRequest instance
  return function ()
  {
    // If the request's status is "complete"
    if (req.readyState == 4)
    {
      // Check that a successful server response was received
      if (req.status == 200)
      {
        // Pass the XML payload of the response to the
        // handler function
        responseXmlHandler(req.responseXML);
      }
      else
      {
        // An HTTP problem has occurred
        alert("HTTP error: "+req.status);
      }
    }
  }
}
/*
 * Returns a function that waits for the specified XMLHttpRequest
 * to complete, then passes its XML response
 * to the given handler function.
 * req - The XMLHttpRequest whose state is changing
 * responseXmlHandler - Function to pass the XML response to
 */
function getReadyStateHandler(req, responseXmlHandler, param1 )
{
  // Return an anonymous function that listens to the
  // XMLHttpRequest instance
  return function ()
  {
    // If the request's status is "complete"
    if (req.readyState == 4)
    {
      // Check that a successful server response was received
      if (req.status == 200)
      {
        // Pass the XML payload of the response to the
        // handler function
        responseXmlHandler(req.responseXML, param1 );
      }
      else
      {
        // An HTTP problem has occurred
        alert("HTTP error: "+req.status);
      }
    }
  }
}

/*
 * Returns a function that waits for the specified XMLHttpRequest
 * to complete, then passes its Text response
 * to the given handler function.
 * req - The XMLHttpRequest whose state is changing
 * responseTextHandler - Function to pass the Text response to
 */
function getReadyStateTextHandler(req, responseTextHandler, param1 )
{
  // Return an anonymous function that listens to the
  // XMLHttpRequest instance
  return function ()
  {
    // If the request's status is "complete"
    if (req.readyState == 4)
    {
      // Check that a successful server response was received
      if (req.status == 200)
      {
        // Pass the XML payload of the response to the
        // handler function
        responseTextHandler(req.responseText, param1 );
      }
      else
      {
        // An HTTP problem has occurred
        alert("HTTP error: "+req.status);
      }
    }
  }
}
